I stayed at the Park Hyatt three times between 2016 and 2018. The concierge staff (at that time, at least) was decent but didn't seem to have particularly well-established connections with hard-to-book restaurants. They were unable to secure reservations to Sukiyabashi Jiro honten in Ginza on any of my stays. (Tokyo Station Hotel is the only hotel that has been able to consistently secure reservations at Jiro for me).

As Morkai stated above, putting together a list of shops via Tabelog based on what looks interesting to you and sending it to the concierge to see what they're able to book would be an excellent way to proceed.

You can check out my Tokyo sushi blog here for some ideas, but keep in mind that everything on there is 3+ years old, so some info is now a little outdated.

https://www.thesushigeek.com/the-sus...%20Restaurants